Magmatism, Uplift and Erosion Along the Continental Margin of SE Brazil

New laser Ar-Ar ages on Parana basalts and rhyolites range in age from 137 to 127 Ma. The inferred minimum eruption rate is therefore an order of magnitude less than those inferred previously for the Parana and other CFB provinces. Chemically defined magma types were erupted at different times in different places, and so within the Parana they should not be regarded as reliable chronostratigraphic units. Magmatism migrated from NW to SE within the Parana, but at a rate 3 times faster than subsequent magmatism along the Rio Grande Rise. It is inferred that lithospheric extension across the Ponta Grossa Arch was a significant component in the generation of the CFB. The results of 65 new apatite ages show that the region has undergone prolonged post break-up erosion and the greatest amounts of material were removed from what is now the low elevation, coastal plain Regional uplift is consistent with significant magmatic underplating, and so it is concluded that the plume related magmatism of the Parana resulted in the generation of significant volumes of new crust, and significantly influenced the subsequent history of uplift and erosion in southern Brazil.